<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>v-on </title>
    <!--  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>-->
    <script src="vue.js"></script>
</head>
<body>
<!-- view -->
<div id="app">
    <button v-on:click="methodAdd($event)">+</button>
    <br>
    {{count}}
    <br>

    <button @click="methodSub('my name is null')">-</button>
</div>
<script>
    let vm = new Vue({
        el: "#app",
        data() {
            return {
                count: 0,
                price: 20,
                totalprice: 0,
                name: ""
            }
        },
        methods: {
            methodSub(name) {
                this.count--;
                console.log(name)
                console.log("count -- "+ this.count)
                // console.log(event)
            },
            methodAdd(event) {
                this.count++;
                alert("count ++"+ this.count)
            }
            //    updateValue

        }
    });
</script>
</body>
</html>
